The invention relates to a luminaire with an array of light emitting diodes (LEDs), and more particularly to a white light emitting luminaire with a control system for adjusting the individual components to maintain a desired color balance (chromaticity).
LEDs are becoming increasingly important as illumination sources for a wide variety of applications. For general illumination and many special applications it is necessary to mix three colors of LED (i.e., red, green, and blue) to produce white light. One way to achieve this is to combine the RED, GREEN, and BLUE LED emissions with appropriate known optics and drive electronics.
U.S. Publication No. US 2001/0032985 A1 discloses an LED luminaire having an array of LEDs including a plurality of LEDs in each of the colors red, green and blue. The LEDs for each color are wired in parallel and provided with a separate power supply and drive electronics displaced from the LED array due to light sensitivity. The chromaticity of the assembly is measured using at least one light sensitive device, and can be controlled (i.e., calibrated) either manually or automatically.
An attractive feature of LED based illumination is the compactness of the illumination source and the small light spot size which can be on the order of tens of microns or less. This allows a high degree of flexibility to maneuver the light generated by means of standard optical components (i.e., lens, reflectors, etc.).
Current LED arrays employ drive electronics displaced from the LED arrays due to light sensitivity. This limits the performance and compactness of LED arrays, as well as increasing the cost of production. Given these limitations, it would be desirable to integrate the drive electronics of an LED array into a single integrated circuit.
The present invention includes integrated drive electronics fabricated in silicon-on-insulator technology resulting in improved white light generation.
In one aspect of the invention, an integrated circuit for controlling an array of LEDs includes at least one signal amplifier, signal processing means, driver means for driving the array of light emitting diodes, at least one switch, and control means for controlling the integrated circuit. In this aspect, the integrated circuit is formed using silicon-on-insulator technology and is selectively shielded from the array of LEDs.
In one embodiment, the integrated circuit is selectively shielded from the array of light emitting diodes by a coating layer.
In several other embodiments, the coating layer is a layer of metal. The metal may be opaque. The metal may also be aluminum.
In another embodiment, the coating layer contacts isolation regions around the integrated circuit.
In another embodiment, at least one metal crossing from the integrated circuit to a terminal of the array of LEDs minimizes light exposure to the active circuits.
In one embodiment, at least one metal crossing from the integrated circuit to a terminal of the array of LEDs minimizes light exposure to the active circuits by the metal coating layer being a meander line configuration surrounded by contact to the integrated circuit. In another embodiment the metal coating layer is coated with a second metal coating layer.
In one aspect of the invention, a luminaire includes an array of LEDs comprising at least one LED in each of a plurality of colors, at least one light sensitive element, and an integrated circuit for controlling the array of LEDs. The integrated circuit includes at least one signal amplifier, signal processing means, driver means for driving the array of light emitting diodes, at least one switch, and control means for controlling the integrated circuit. The integrated circuit also includes silicon-on-insulator and is selectively shielded from the array of light emitting diodes. In addition, at least one light sensitive element is exposed to the array of LEDs.
In one embodiment, at least one light sensing element further comprises at least one photo detector. In another embodiment, at least one photo detector is in substantial proximity to at least one LED in the array of LEDs.
In another aspect of the invention, a method of manufacturing an integrated circuit for controlling an array of LEDs includes the steps of incorporating drive electronics for the array of LEDs into a single silicon-on-insulator integrated circuit; selectively shielding the drive electronics; and mounting the array of LEDs on the integrated circuit.
The invention provides many advantages that are evident from the following description, drawings, and claims.